A catalytic converter assembly has a ceramic substrate body with a plurality of cells for passage therethrough of exhaust gases. An emitter electrode for emitting free electrodes is mounted adjacent the substrate body for intercepting exhaust gas flowing at an upstream location of the catalytic converter. A collector electrode for collecting electrons is mounted adjacent the substrate body to intercept exhaust gas flowing at a downstream location of the catalytic converter. An energizing circuit is used to apply a high voltage between the emitter and collector to stimulate the generation of free electrons.